1. Field of the Invention
The present invention relates to an image forming apparatus which forms an image on a free-size sheet having an arbitrary size other than regular sizes.
2. Related Background Art
Generally, in an image forming apparatus such as a copy machine, a printer or the like, a paper feeding device which has a recording paper cassette putting (or loading) recording paper has been widely used. In the recording paper cassette, there are a recording paper cassette putting the recording paper of a regular size such as an A4 size, an A3 size or the like and a free-size cassette capable of putting the recording paper of an arbitrary size.
In the image forming apparatus capable of having such the free-size cassette, a size (longitudinal and lateral dimensions) of the recording paper put in this free-size cassette is designated by a user through a key operation, and controlling of image forming on the recording paper is adaptively performed according to such the designated recording-paper size. Concretely, the recording-paper size is designated at accuracy in the unit of millimeter or less, an operation condition about the image forming on the recording paper is set based on the designated recording-paper size, and the controlling is performed according to the set operation condition. By setting the operation condition about the image forming on the recording paper based on the designated recording-paper size and performing the control according to the set operation condition in this way, it is realized that the optimum image is formed on the recording paper the size of which was designated.
However, in such a method as the operation condition about the image forming on the recording paper is set based on the designated recording-paper size and the image forming is controlled based on the set condition, even if the operation condition may be set as the condition which is not influenced by a slight difference of the recording-paper size, it is possible that the operation condition is set as a more strict condition than is necessary. Therefore, there is some fear that the controlling becomes complicated.
On the other hand, if the designated recording-paper size is equal to or less than a predetermined size, there can be supposed a method that the designated recording-paper size is considered as a maximum size within a range capable of being handled and the operation condition is set based on this maximum size, and in this method the controlling does not become complicated. However, an optimal throughput according to each recording-paper size can not be obtained.
An object of the present invention is to provide an image forming apparatus which solved such problems as described above.
Another object of the present invention to provide an image forming apparatus which can, in a case where image forming is performed on a free-size sheet (or paper) having an arbitrary size other than regular sizes, perform controlling suitable for such the sheet size without lowering a throughput and making the controlling complicated.
The above and other objects, features, and advantages of the present invention will be apparent from the following detailed description and the appended claims in conjunction with the accompanying drawings.